Enhancing the light harvesting efficiency, open circuit voltage and stability of molybdenum doped ZnO nanocluster in dye-sensitized solar cells: (A DFT study)

In this study, the electronic and structural properties of drum structured Mo-doped ZnO (MoZnO) cluster as the π conjugated bridging in the dye-sensitized solar cells (DSSC) were compared with its pristine form by density functional theory (DFT) calculations under Gaussian 09 Program. The frontier molecular orbital study was explored to determine the charge transport characteristics of donor-acceptor moieties over the entire visible range and the electron injection from the valence band (LUMO) orbital to the conduction band (HOMO) orbital of MoZnO. The energy gap (Eg), binding energy (EB), global reactivity descriptors, thermodynamic parameters and the dipole moment were also calculated for MoZnO and compared with ZnO. The density of states (DOS) of MoZnO material was investigated to demonstrate the importance of d orbital of Mo atom in hybridization. To examine the charge distribution, Mulliken atomic charge distribution and molecular electrostatic potential (MEP) were analyzed. A spectroscopic study was included for the better perception of the interaction of Mo with ZnO cluster. The increased value of the first-order hyperpolarizability of MoZnO from its pure cluster manifests the MoZnO is a better candidate with the superior nonlinear optical property. The analysis of UV-Vis spectra through the time-dependent density functional theory (TD-DFT) discovers that the MoZnO has larger light harvesting efficiency (LHE) which influences the higher photon to current conversion efficiency. As a result, the valence band (LUMO) of MoZnO is intense than the conduction band (HOMO) of MoZnO making an increase in the open circuit voltage (VOC) and hence it confirms that the MoZnO material can be a used in photovoltaic applications.